prep for 1.8 release

[bkmartinjr]

Changes:

• update cellxgene-census package python dependency to tiledbsoma~=1.5.1
• update R version number
• mark X_sparse_iter as deprecated
• updated obsolete copyright notices

Fixes: #801
Fixes: #36
Fixes: #815

Note: builder deps are unchanged.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (505a0f2) 85.85% compared to head (efebadb) 85.85%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #852   +/-   ##
=======================================
  Coverage   85.85%   85.85%           
=======================================
  Files          70       70           
  Lines        5167     5167           
=======================================
  Hits         4436     4436           
  Misses        731      731           

Flag	Coverage Δ
unittests	85.85% <ø> (ø)

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[bkmartinjr]

Tagging @maniarathi for a review to confirm Foundation name changes